As per title of thread - a note regarding the license and description of the black van that hit my stationary car was left inside the wing mirror casing. No contact details of the person who wrote the note were given, so it would not be possible to ask them to be a witness. The incident was on the corner of Thrale Street, just leading of Southwark Street.
Miss Marple tactics are unlikely to work. It sounds like a bystander rather than the driver left the information anyway.
Your insurer will find out the vehicle's driver/owner from DVLA. Do this quickly and the police may be able to check if the vehicle bears the damage that proves it was involved. If the police want to do them for not stopping at the scene, they will do that too.